/*
 * Copyright 2019 FormDev Software GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.formdev.flatlaf.ui;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.KeyboardFocusManager;
import java.awt.Paint;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.SystemColor;
import java.awt.Toolkit;
import java.awt.Window;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.util.IdentityHashMap;
import java.util.WeakHashMap;
import java.util.function.Predicate;
import java.util.function.Supplier;
import javax.swing.Icon;
import javax.swing.JComponent;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.LookAndFeel;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.UIDefaults;
import javax.swing.UIManager;
import javax.swing.border.Border;
import javax.swing.border.CompoundBorder;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.UIResource;
import javax.swing.tree.DefaultTreeCellEditor;
import com.formdev.flatlaf.FlatClientProperties;
import com.formdev.flatlaf.FlatIntelliJLaf;
import com.formdev.flatlaf.FlatLaf;
import com.formdev.flatlaf.FlatLightLaf;
import com.formdev.flatlaf.FlatSystemProperties;
import com.formdev.flatlaf.util.DerivedColor;
import com.formdev.flatlaf.util.Graphics2DProxy;
import com.formdev.flatlaf.util.HiDPIUtils;
import com.formdev.flatlaf.util.SystemInfo;
import com.formdev.flatlaf.util.UIScale;

/**
 * Utility methods for UI delegates.
 *
 * @author Karl Tauber
 */
public class FlatUIUtils
{
	private static boolean useSharedUIs = true;
	private static final WeakHashMap<LookAndFeel, IdentityHashMap<Object, ComponentUI>> sharedUIinstances = new WeakHashMap<>();

	public static Rectangle addInsets( Rectangle r, Insets insets ) {
		return new Rectangle(
			r.x - insets.left,
			r.y - insets.top,
			r.width + insets.left + insets.right,
			r.height + insets.top + insets.bottom );
	}

	public static Rectangle subtractInsets( Rectangle r, Insets insets ) {
		return new Rectangle(
			r.x + insets.left,
			r.y + insets.top,
			r.width - insets.left - insets.right,
			r.height - insets.top - insets.bottom );
	}

	public static Dimension addInsets( Dimension dim, Insets insets ) {
		return new Dimension(
			dim.width + insets.left + insets.right,
			dim.height + insets.top + insets.bottom );
	}

	public static Insets addInsets( Insets insets1, Insets insets2 ) {
		if( insets1 == null )
			return insets2;
		if( insets2 == null )
			return insets1;

		return new Insets(
			insets1.top + insets2.top,
			insets1.left + insets2.left,
			insets1.bottom + insets2.bottom,
			insets1.right + insets2.right );
	}

	public static void setInsets( Insets dest, Insets src ) {
		dest.top = src.top;
		dest.left = src.left;
		dest.bottom = src.bottom;
		dest.right = src.right;
	}

	/** @since 3.5 */
	public static boolean isInsetsEmpty( Insets insets ) {
		return insets.top == 0 && insets.left == 0 && insets.bottom == 0 && insets.right == 0;
	}

	/** @since 3.6 */
	public static Color stateColor( boolean state, Color stateColor, Color defaultColor ) {
		return (state && stateColor != null) ? stateColor : defaultColor;
	}

	/** @since 3.6 */
	public static Color stateColor( boolean state1, Color state1Color,
		boolean state2, Color state2Color, Color defaultColor )
	{
		return (state1 && state1Color != null)
			? state1Color
			: ((state2 && state2Color != null) ? state2Color : defaultColor);
	}

	public static Color getUIColor( String key, int defaultColorRGB ) {
		Color color = UIManager.getColor( key );
		return (color != null) ? color : new Color( defaultColorRGB );
	}

	public static Color getUIColor( String key, Color defaultColor ) {
		Color color = UIManager.getColor( key );
		return (color != null) ? color : defaultColor;
	}

	public static Color getUIColor( String key, String defaultKey ) {
		Color color = UIManager.getColor( key );
		return (color != null) ? color : UIManager.getColor( defaultKey );
	}

	/** @since 1.1 */
	public static boolean getUIBoolean( String key, boolean defaultValue ) {
		Object value = UIManager.get( key );
		return (value instanceof Boolean) ? (Boolean) value : defaultValue;
	}

	public static int getUIInt( String key, int defaultValue ) {
		Object value = UIManager.get( key );
		return (value instanceof Integer) ? (Integer) value : defaultValue;
	}

	public static float getUIFloat( String key, float defaultValue ) {
		Object value = UIManager.get( key );
		return (value instanceof Number) ? ((Number)value).floatValue() : defaultValue;
	}

	/** @since 2 */
	public static <T extends Enum<T>> T getUIEnum( String key, Class<T> enumType, T defaultValue ) {
		Object value = UIManager.get( key );
		if( value instanceof String ) {
			try {
				return Enum.valueOf( enumType, (String) value );
			} catch( IllegalArgumentException ex ) {
				// ignore
			}
		}
		return defaultValue;
	}

	/** @since 3.2 */
	public static Color getSubUIColor( String key, String subKey ) {
		if( subKey != null ) {
			Color value = UIManager.getColor( buildSubKey( key, subKey ) );
			if( value != null )
				return value;
		}
		return UIManager.getColor( key );
	}

	/** @since 3.2 */
	public static boolean getSubUIBoolean( String key, String subKey, boolean defaultValue ) {
		if( subKey != null ) {
			Object value = UIManager.get( buildSubKey( key, subKey ) );
			if( value instanceof Boolean )
				return (Boolean) value;
		}
		return getUIBoolean( key, defaultValue );
	}

	/** @since 3.2 */
	public static int getSubUIInt( String key, String subKey, int defaultValue ) {
		if( subKey != null ) {
			Object value = UIManager.get( buildSubKey( key, subKey ) );
			if( value instanceof Integer )
				return (Integer) value;
		}
		return getUIInt( key, defaultValue );
	}

	/** @since 3.2 */
	public static Insets getSubUIInsets( String key, String subKey ) {
		if( subKey != null ) {
			Insets value = UIManager.getInsets( buildSubKey( key, subKey ) );
			if( value != null )
				return value;
		}
		return UIManager.getInsets( key );
	}

	/** @since 3.2 */
	public static Dimension getSubUIDimension( String key, String subKey ) {
		if( subKey != null ) {
			Dimension value = UIManager.getDimension( buildSubKey( key, subKey ) );
			if( value != null )
				return value;
		}
		return UIManager.getDimension( key );
	}

	/** @since 3.2 */
	public static Icon getSubUIIcon( String key, String subKey ) {
		if( subKey != null ) {
			Icon value = UIManager.getIcon( buildSubKey( key, subKey ) );
			if( value != null )
				return value;
		}
		return UIManager.getIcon( key );
	}

	/** @since 3.2 */
	public static Font getSubUIFont( String key, String subKey ) {
		if( subKey != null ) {
			Font value = UIManager.getFont( buildSubKey( key, subKey ) );
			if( value != null )
				return value;
		}
		return UIManager.getFont( key );
	}

	/**
	 * Inserts {@code subKey} at last dot in {@code key}.
	 * <p>
	 * E.g. {@code buildSubKey( "TitlePane.font", "small" )} returns {@code "TitlePane.small.font"}.
	 */
	private static String buildSubKey( String key, String subKey ) {
		int dot = key.lastIndexOf( '.' );
		return (dot >= 0)
			? key.substring( 0, dot ) + '.' + subKey + '.' + key.substring( dot + 1 )
			: key;
	}

	/** @since 1.1.2 */
	public static boolean getBoolean( JComponent c, String systemPropertyKey,
		String clientPropertyKey, String uiKey, boolean defaultValue )
	{
		// check whether forced to true/false via system property
		Boolean value = FlatSystemProperties.getBooleanStrict( systemPropertyKey, null );
		if( value != null )
			return value;

		// check whether forced to true/false via client property
		value = FlatClientProperties.clientPropertyBooleanStrict( c, clientPropertyKey, null );
		if( value != null )
			return value;

		return getUIBoolean( uiKey, defaultValue );
	}

	public static boolean isChevron( String arrowType ) {
		return !"triangle".equals( arrowType );
	}

	public static Color nonUIResource( Color c ) {
		return (c instanceof UIResource) ? new Color( c.getRGB(), true ) : c;
	}

	public static Font nonUIResource( Font font ) {
		return (font instanceof UIResource) ? font.deriveFont( font.getStyle() ) : font;
	}

	/** @since 2 */
	public static Border nonUIResource( Border border ) {
		return (border instanceof UIResource) ? new NonUIResourceBorder( border ) : border;
	}

	static Border unwrapNonUIResourceBorder( Border border ) {
		return (border instanceof NonUIResourceBorder) ? ((NonUIResourceBorder)border).delegate : border;
	}

	public static int minimumWidth( JComponent c, int minimumWidth ) {
		return FlatClientProperties.clientPropertyInt( c, FlatClientProperties.MINIMUM_WIDTH, minimumWidth );
	}

	public static int minimumHeight( JComponent c, int minimumHeight ) {
		return FlatClientProperties.clientPropertyInt( c, FlatClientProperties.MINIMUM_HEIGHT, minimumHeight );
	}

	public static boolean isCellEditor( Component c ) {
		if( c == null )
			return false;

		// check whether used as table cell editor
		Container parent = c.getParent();
		if( parent instanceof JTable && ((JTable)parent).getEditorComponent() == c )
			return true;

		// check whether used as tree cell editor
		if( parent instanceof DefaultTreeCellEditor.EditorContainer )
			return true;

		// check whether used as cell editor
		//   Table.editor is set in JTable.GenericEditor constructor
		//   Tree.cellEditor is set in sun.swing.FilePane.editFileName()
		String name = c.getName();
		if( "Table.editor".equals( name ) || "Tree.cellEditor".equals( name ) )
			return true;

		// for using combo box as cell editor in table
		//   JComboBox.isTableCellEditor is set in javax.swing.DefaultCellEditor(JComboBox) constructor
		return c instanceof JComponent && Boolean.TRUE.equals( ((JComponent)c).getClientProperty( "JComboBox.isTableCellEditor" ) );
	}

	/**
	 * Returns whether the given component is the permanent focus owner and
	 * is in the active window or in a popup window owned by the active window.
	 * Used to paint focus indicators.
	 */
	@SuppressWarnings( "unchecked" )
	public static boolean isPermanentFocusOwner( Component c ) {
		KeyboardFocusManager keyboardFocusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();

		if( c instanceof JComponent ) {
			Object value = ((JComponent)c).getClientProperty( FlatClientProperties.COMPONENT_FOCUS_OWNER );
			if( value instanceof Predicate ) {
				return ((Predicate<JComponent>)value).test( (JComponent) c ) &&
					isInActiveWindow( c, keyboardFocusManager.getActiveWindow() );
			}
		}

		// invoke hasFocus() here because components may have overridden this method
		// (e.g. Swing delegate components used for AWT components on macOS)
		if( c.hasFocus() )
			return true;

		return keyboardFocusManager.getPermanentFocusOwner() == c &&
			isInActiveWindow( c, keyboardFocusManager.getActiveWindow() );
	}

	static boolean isInActiveWindow( Component c, Window activeWindow ) {
		Window window = SwingUtilities.windowForComponent( c );
		return window == activeWindow ||
			(window != null && window.getType() == Window.Type.POPUP && window.getOwner() == activeWindow);
	}

	static boolean isAWTPeer( Component c ) {
		// on macOS, Swing components are used for AWT components
		if( SystemInfo.isMacOS )
			return c.getClass().getName().startsWith( "sun.lwawt.LW" );
		return false;
	}

	/**
	 * Checks whether component is used as peer for AWT (on macOS) and
	 * whether a dark FlatLaf theme is active, which requires special handling
	 * because AWT always uses light colors.
	 */
	static boolean needsLightAWTPeer( JComponent c ) {
		return FlatUIUtils.isAWTPeer( c ) && FlatLaf.isLafDark();
	}

	private static UIDefaults lightAWTPeerDefaults;

	static void runWithLightAWTPeerUIDefaults( Runnable runnable ) {
		if( lightAWTPeerDefaults == null ) {
			FlatLaf lightLaf = UIManager.getInt( "Component.focusWidth" ) >= 2
				? new FlatIntelliJLaf()
				: new FlatLightLaf();
			lightAWTPeerDefaults = lightLaf.getDefaults();
		}

		FlatLaf.runWithUIDefaultsGetter( key -> {
			Object value = lightAWTPeerDefaults.get( key );
			return (value != null) ? value : FlatLaf.NULL_VALUE;
		}, runnable );
	}

	/**
	 * Returns whether the given component is in a window that is in full-screen mode.
	 */
	public static boolean isFullScreen( Component c ) {
		GraphicsConfiguration gc = c.getGraphicsConfiguration();
		GraphicsDevice gd = (gc != null) ? gc.getDevice() : null;
		Window fullScreenWindow = (gd != null) ? gd.getFullScreenWindow() : null;
		return (fullScreenWindow != null && fullScreenWindow == SwingUtilities.windowForComponent( c ));
	}

	/** @since 3.6.1 */
	public static Insets getScreenInsets( GraphicsConfiguration gc ) {
		// on Linux, getScreenInsets() may report wrong values in multi-screen setups
		// see https://github.com/apache/netbeans/issues/8532#issuecomment-2909687016
		if( SystemInfo.isLinux &&
			GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices().length > 1 )
		  return new Insets( 0, 0, 0, 0 );

		return Toolkit.getDefaultToolkit().getScreenInsets( gc );
	}

	public static Boolean isRoundRect( Component c ) {
		return (c instanceof JComponent)
			? FlatClientProperties.clientPropertyBooleanStrict(
				(JComponent) c, FlatClientProperties.COMPONENT_ROUND_RECT, null )
			: null;
	}

	/**
	 * Returns the scaled thickness of the outer focus border for the given component.
	 */
	public static float getBorderFocusWidth( JComponent c ) {
		FlatBorder border = getOutsideFlatBorder( c );
		return (border != null)
			? UIScale.scale( (float) border.getFocusWidth( c ) )
			: 0;
	}

	/**
	 * Returns the scaled line thickness used to compute the border insets.
	 *
	 * @since 2
	 */
	public static float getBorderLineWidth( JComponent c ) {
		FlatBorder border = getOutsideFlatBorder( c );
		return (border != null)
			? UIScale.scale( (float) border.getLineWidth( c ) )
			: 0;
	}

	/**
	 * Returns the scaled thickness of the border.
	 * This includes the outer focus border and the actual component border.
	 *
	 * @since 2
	 */
	public static int getBorderFocusAndLineWidth( JComponent c ) {
		FlatBorder border = getOutsideFlatBorder( c );
		return (border != null)
			? Math.round( UIScale.scale( (float) border.getFocusWidth( c ) )
				+ UIScale.scale( (float) border.getLineWidth( c ) ) )
			: 0;
	}

	/**
	 * Returns the scaled arc diameter of the border for the given component.
	 */
	public static float getBorderArc( JComponent c ) {
		FlatBorder border = getOutsideFlatBorder( c );
		return (border != null)
			? UIScale.scale( (float) border.getArc( c ) )
			: 0;
	}

	public static boolean hasRoundBorder( JComponent c ) {
		return getBorderArc( c ) >= c.getHeight();
	}

	public static FlatBorder getOutsideFlatBorder( JComponent c ) {
		Border border = c.getBorder();
		for(;;) {
			if( border instanceof FlatBorder )
				return (FlatBorder) border;
			else if( border instanceof CompoundBorder )
				border = ((CompoundBorder)border).getOutsideBorder();
			else
				return null;
		}
	}

	/**
	 * Sets rendering hints used for painting.
	 */
	public static Object[] setRenderingHints( Graphics g ) {
		Graphics2D g2 = (Graphics2D) g;
		Object[] oldRenderingHints = {
			g2.getRenderingHint( RenderingHints.KEY_ANTIALIASING ),
			g2.getRenderingHint( RenderingHints.KEY_STROKE_CONTROL ),
		};

		g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON );
		g2.setRenderingHint( RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_NORMALIZE );

		return oldRenderingHints;
	}

	/**
	 * Resets rendering hints previously set with {@link #setRenderingHints}.
	 */
	public static void resetRenderingHints( Graphics g, Object[] oldRenderingHints ) {
		Graphics2D g2 = (Graphics2D) g;
		if( oldRenderingHints[0] != null )
			g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, oldRenderingHints[0] );
		if( oldRenderingHints[1] != null )
			g2.setRenderingHint( RenderingHints.KEY_STROKE_CONTROL, oldRenderingHints[1] );
	}

	/**
	 * Temporary resets rendering hints set with {@link #setRenderingHints}
	 * and runs the given runnable.
	 * <p>
	 * This is intended for painting text while rendering hints are set.
	 * <p>
	 * If text antialiasing is disabled (in OS system settings or via
	 * {@code -Dawt.useSystemAAFontSettings=off}), but general antialiasing is enabled,
	 * then text is still painted using some kind of "grayscale" antialiasing,
	 * which may make the text look bold (depends on font and font size).
	 * To avoid this, temporary disable general antialiasing.
	 * This does not affect text rendering if text antialiasing is enabled (usually the default).
	 */
	public static void runWithoutRenderingHints( Graphics g, Object[] oldRenderingHints, Runnable runnable ) {
		if( oldRenderingHints == null ) {
			runnable.run();
			return;
		}

		Graphics2D g2 = (Graphics2D) g;
		Object[] oldRenderingHints2 = {
			g2.getRenderingHint( RenderingHints.KEY_ANTIALIASING ),
			g2.getRenderingHint( RenderingHints.KEY_STROKE_CONTROL ),
		};

		resetRenderingHints( g2, oldRenderingHints );
		runnable.run();
		resetRenderingHints( g2, oldRenderingHints2 );
	}

	public static Color deriveColor( Color color, Color baseColor ) {
		return (color instanceof DerivedColor)
			? ((DerivedColor)color).derive( baseColor )
			: color;
	}

	/**
	 * Fills the background of a component with a rounded rectangle.
	 * <p>
	 * The bounds of the painted rounded rectangle are
	 * {@code x + focusWidth, y + focusWidth, width - (focusWidth * 2), height - (focusWidth * 2)}.
	 * The given arc diameter refers to the painted rectangle (and not to {@code x,y,width,height}).
	 *
	 * @see #paintOutlinedComponent
	 */
	public static void paintComponentBackground( Graphics2D g, int x, int y, int width, int height,
		float focusWidth, float arc )
	{
		paintOutlinedComponent( g, x, y, width, height, focusWidth, 0, 0, 0, arc, null, null, g.getPaint() );
	}

	/**
	 * Paints an outlined component with rounded corners, consisting of following parts:
	 * <ul>
	 * <li>an (optional) outer border, which is usually a focus indicator
	 * <li>an (optional) component border
	 * <li>the (optional) component background
	 * </ul>
	 * <p>
	 *
	 * Each part is painted only if the corresponding part color is not {@code null}.
	 * The parts are painted in this order:
	 * <ol>
	 * <li>background
	 * <li>focus border
	 * <li>border
	 * </ol>
	 * <p>
	 *
	 * <strong>Background</strong>:
	 * The bounds of the filled rounded rectangle are
	 * {@code [x + focusWidth, y + focusWidth, width - (focusWidth * 2), height - (focusWidth * 2)]}.
	 * The focus border and the border may paint over the background.
	 * <p>
	 *
	 * <strong>Focus border</strong>:
	 * The outside bounds of the painted focus border are {@code [x, y, width, height]}.
	 * The thickness of the painted focus border is {@code (focusWidth * focusWidthFraction) + focusInnerWidth}.
	 * The border may paint over the focus border if {@code focusInnerWidth > 0}.
	 * <p>
	 *
	 * <strong>Border</strong>:
	 * The outside bounds of the painted border are
	 * {@code [x + focusWidth, y + focusWidth, width - (focusWidth * 2), height - (focusWidth * 2)]}.
	 * The thickness of the painted border is {@code borderWidth}.
	 *
	 * @param g the graphics context used for painting
	 * @param x the x coordinate of the component
	 * @param y the y coordinate of the component
	 * @param width the width of the component
	 * @param height the height of the component
	 * @param focusWidth the width of the focus border, or {@code 0}
	 * @param focusWidthFraction specified how much of the focus border is painted (in range 0 - 1);
	 *                           can be used for animation;
	 *                           the painted thickness of the focus border is {@code (focusWidth * focusWidthFraction) + focusInnerWidth}
	 * @param focusInnerWidth the inner width of the focus border, or {@code 0};
	 *                        if a border is painted then {@code focusInnerWidth} needs to be larger
	 *                        than {@code borderWidth} to be not hidden by the border
	 * @param borderWidth the width of the border, or {@code 0}
	 * @param arc the arc diameter used for the outside shape of the component border;
	 *            the other needed arc diameters are computed from this arc diameter
	 * @param focusColor the color of the focus border, or {@code null}
	 * @param borderColor the color of the border, or {@code null}
	 * @param background the background color of the component, or {@code null}
	 *
	 * @since 2
	 */
	public static void paintOutlinedComponent( Graphics2D g, int x, int y, int width, int height,
		float focusWidth, float focusWidthFraction, float focusInnerWidth, float borderWidth, float arc,
		Paint focusColor, Paint borderColor, Paint background )
	{
		paintOutlinedComponent( g, x, y, width, height, focusWidth, focusWidthFraction, focusInnerWidth,
			borderWidth, arc, focusColor, borderColor, background, false );
	}

	static void paintOutlinedComponent( Graphics2D g, int x, int y, int width, int height,
		float focusWidth, float focusWidthFraction, float focusInnerWidth, float borderWidth, float arc,
		Paint focusColor, Paint borderColor, Paint background, boolean scrollPane )
	{
		double systemScaleFactor = UIScale.getSystemScaleFactor( g );
		if( (int) systemScaleFactor != systemScaleFactor ) {
			// paint at scale 1x to avoid clipping on right and bottom edges at 125%, 150% or 175%
			HiDPIUtils.paintAtScale1x( g, x, y, width, height,
				(g2d, x2, y2, width2, height2, scaleFactor) -> {
					paintOutlinedComponentImpl( g2d, x2, y2, width2, height2,
						(float) (focusWidth * scaleFactor), focusWidthFraction, (float) (focusInnerWidth * scaleFactor),
						(float) (borderWidth * scaleFactor), (float) (arc * scaleFactor),
						focusColor, borderColor, background, scrollPane, scaleFactor );
				} );
			return;
		}

		paintOutlinedComponentImpl( g, x, y, width, height, focusWidth, focusWidthFraction, focusInnerWidth,
			borderWidth, arc, focusColor, borderColor, background, scrollPane, systemScaleFactor );
	}

	@SuppressWarnings( "SelfAssignment" ) // Error Prone
	private static void paintOutlinedComponentImpl( Graphics2D g, int x, int y, int width, int height,
		float focusWidth, float focusWidthFraction, float focusInnerWidth, float borderWidth, float arc,
		Paint focusColor, Paint borderColor, Paint background, boolean scrollPane, double scaleFactor )
	{
		// Special handling for scrollpane and fractional scale factors (e.g. 1.25 - 1.75),
		// where Swing scales one "logical" pixel (border insets) to either one or two physical pixels.
		// Antialiasing is used to paint the border, which usually needs two physical pixels
		// at small scale factors. 1px for the solid border and another 1px for antialiasing.
		// But scrollpane view is painted over the border, which results in a painted border
		// that is 1px thick at some sides and 2px thick at other sides.
		if( scrollPane && scaleFactor != (int) scaleFactor ) {
			if( focusWidth > 0 ) {
				// reduce outer border thickness (focusWidth) so that inner side of
				// component border (focusWidth + borderWidth) is at a full pixel
				int totalWidth = (int) (focusWidth + borderWidth);
				focusWidth = totalWidth - borderWidth;
			} else {// if( scaleFactor > 1 && scaleFactor < 2 ) {
				// reduce component border thickness (borderWidth) to full pixels
				borderWidth = (int) borderWidth;
			}
		}

		// outside bounds of the border and the background
		float x1 = x + focusWidth;
		float y1 = y + focusWidth;
		float w1 = width - focusWidth * 2;
		float h1 = height - focusWidth * 2;

		// fill background
		//   bounds: x + focusWidth, y + focusWidth, width - (focusWidth * 2), height - (focusWidth * 2)
		//   arc diameter: arc
		if( background != null ) {
			g.setPaint( background );
			g.fill( createComponentRectangle( x1, y1, w1, h1, arc ) );
		}

		// optimization: paint focus border and border in single operation if colors are equal
		if( borderColor != null && borderColor.equals( focusColor ) ) {
			borderColor = null;
			focusInnerWidth = Math.max( focusInnerWidth, borderWidth );
		}

		// paint focus border
		//   outer bounds: x, y, width, height
		//   thickness: focusWidth + focusInnerWidth
		//   outer arc diameter: arc + (focusWidth * 2)
		//   inner arc diameter: arc - (focusInnerWidth * 2)
		float paintedFocusWidth = (focusWidth * focusWidthFraction) + focusInnerWidth;
		if( focusColor != null && paintedFocusWidth != 0 ) {
			// outside bounds of the focus border
			float inset = focusWidth - (focusWidth * focusWidthFraction);
			float x2 = x + inset;
			float y2 = y + inset;
			float w2 = width - (inset * 2);
			float h2 = height - (inset * 2);

			float outerArc = arc + (focusWidth * 2);
			float innerArc = arc - (focusInnerWidth * 2);

			// reduce outer arc slightly for small arcs to make the curve slightly wider
			if( focusWidth > 0 && arc > 0 && arc < UIScale.scale( 10 ) )
				outerArc -= UIScale.scale( 2f );

			// consider focus width fraction
			if( focusWidthFraction != 1 )
				outerArc = arc + ((outerArc - arc) * focusWidthFraction);

			g.setPaint( focusColor );
			paintOutline( g, x2, y2, w2, h2, paintedFocusWidth, outerArc, innerArc );
		}

		// paint border
		//   outer bounds: x + focusWidth, y + focusWidth, width - (focusWidth * 2), height - (focusWidth * 2)
		//   thickness: borderWidth
		//   outer arc diameter: arc
		//   inner arc diameter: arc - (borderWidth * 2)
		if( borderColor != null && borderWidth != 0 ) {
			g.setPaint( borderColor );
			paintOutline( g, x1, y1, w1, h1, borderWidth, arc );
		}
	}

	/**
	 * Paints an outline at the given bounds using the given line width.
	 * Depending on the given arc, a rectangle, rounded rectangle or circle (if w == h) is painted.
	 *
	 * @param g the graphics context used for painting
	 * @param x the x coordinate of the outline
	 * @param y the y coordinate of the outline
	 * @param w the width of the outline
	 * @param h the height of the outline
	 * @param lineWidth the width of the outline
	 * @param arc the arc diameter used for the outside shape of the outline
	 *
	 * @since 2
	 */
	public static void paintOutline( Graphics2D g, float x, float y, float w, float h,
		float lineWidth, float arc )
	{
		paintOutline( g, x, y, w, h, lineWidth, arc, arc - (lineWidth * 2) );
	}

	/**
	 * Paints an outline at the given bounds using the given line width.
	 * Depending on the given arc, a rectangle, rounded rectangle or circle (if w == h) is painted.
	 *
	 * @param g the graphics context used for painting
	 * @param x the x coordinate of the outline
	 * @param y the y coordinate of the outline
	 * @param w the width of the outline
	 * @param h the height of the outline
	 * @param lineWidth the width of the outline
	 * @param arc the arc diameter used for the outside shape of the outline
	 * @param innerArc the arc diameter used for the inside shape of the outline
	 *
	 * @since 2
	 */
	public static void paintOutline( Graphics2D g, float x, float y, float w, float h,
		float lineWidth, float arc, float innerArc )
	{
		if( lineWidth == 0 || w <= 0 || h <= 0 )
			return;

		float t = lineWidth;
		float t2x = t * 2;

		Path2D border = new Path2D.Float( Path2D.WIND_EVEN_ODD );
		border.append( createComponentRectangle( x, y, w, h, arc ), false );
		border.append( createComponentRectangle( x + t, y + t, w - t2x, h - t2x, innerArc ), false );
		g.fill( border );
	}

	/**
	 * Creates a (rounded) rectangle used to paint components (border, background, etc.).
	 * The given arc diameter is limited to min(width,height).
	 */
	public static Shape createComponentRectangle( float x, float y, float w, float h, float arc ) {
		if( arc <= 0 )
			return new Rectangle2D.Float( x, y, w, h );

		if( w == h && arc >= w )
			return new Ellipse2D.Float( x, y, w, h );

		arc = Math.min( arc, Math.min( w, h ) );
		return new RoundRectangle2D.Float( x, y, w, h, arc, arc );
	}

	static void paintFilledRectangle( Graphics g, Color color, float x, float y, float w, float h ) {
		Graphics2D g2 = (Graphics2D) g.create();
		try {
			FlatUIUtils.setRenderingHints( g2 );
			g2.setColor( color );
			g2.fill( new Rectangle2D.Float( x, y, w, h ) );
		} finally {
			g2.dispose();
		}
	}

	/**
	 * Paints a selection.
	 * <p>
	 * The bounds of the painted selection (rounded) rectangle are
	 * {@code x + insets.left, y + insets.top, width - insets.left - insets.right, height - insets.top - insets.bottom}.
	 * The given arc radius refers to the painted rectangle (and not to {@code x,y,width,height}).
	 *
	 * @since 3
	 */
	public static void paintSelection( Graphics2D g, int x, int y, int width, int height, Insets insets,
		float arcTopLeft, float arcTopRight, float arcBottomLeft, float arcBottomRight, int flags )
	{
		if( insets != null ) {
			x += insets.left;
			y += insets.top;
			width -= insets.left + insets.right;
			height -= insets.top + insets.bottom;
		}

		if( arcTopLeft > 0 || arcTopRight > 0 || arcBottomLeft > 0 || arcBottomRight > 0 ) {
			double systemScaleFactor = UIScale.getSystemScaleFactor( g );
			if( systemScaleFactor != (int) systemScaleFactor ) {
				// paint at scale 1x to avoid clipping on right and bottom edges at 125%, 150% or 175%
				HiDPIUtils.paintAtScale1x( g, x, y, width, height,
					(g2d, x2, y2, width2, height2, scaleFactor) -> {
						paintRoundedSelectionImpl( g2d, x2, y2, width2, height2,
							(float) (arcTopLeft * scaleFactor), (float) (arcTopRight * scaleFactor),
							(float) (arcBottomLeft * scaleFactor), (float) (arcBottomRight * scaleFactor) );
					} );
			} else
				paintRoundedSelectionImpl( g, x, y, width, height, arcTopLeft, arcTopRight, arcBottomLeft, arcBottomRight );

		} else
			g.fillRect( x, y, width, height );
	}

	private static void paintRoundedSelectionImpl( Graphics2D g, int x, int y, int width, int height,
		float arcTopLeft, float arcTopRight, float arcBottomLeft, float arcBottomRight )
	{
		Object[] oldRenderingHints = FlatUIUtils.setRenderingHints( g );
		g.fill( FlatUIUtils.createRoundRectanglePath( x, y, width, height, arcTopLeft, arcTopRight, arcBottomLeft, arcBottomRight ) );
		FlatUIUtils.resetRenderingHints( g, oldRenderingHints );
	}

	public static void paintGrip( Graphics g, int x, int y, int width, int height,
		boolean horizontal, int dotCount, int dotSize, int gap, boolean centerPrecise )
	{
		dotSize = UIScale.scale( dotSize );
		gap = UIScale.scale( gap );
		int gripSize = (dotSize * dotCount) + (gap * (dotCount - 1));

		// calculate grip position
		float gx;
		float gy;
		if( horizontal ) {
			gx = x + Math.round( (width - gripSize) / 2f );
			gy = y + ((height - dotSize) / 2f);

			if( !centerPrecise )
				gy = Math.round( gy );
		} else {
			// vertical
			gx = x + ((width - dotSize) / 2f);
			gy = y + Math.round( (height - gripSize) / 2f );

			if( !centerPrecise )
				gx = Math.round( gx );
		}

		// paint dots
		for( int i = 0; i < dotCount; i++ ) {
			((Graphics2D)g).fill( new Ellipse2D.Float( gx, gy, dotSize, dotSize ) );
			if( horizontal )
				gx += dotSize + gap;
			else
				gy += dotSize + gap;
		}
	}

	/**
	 * Fill background with parent's background color because the visible component
	 * is smaller than its bounds (for the focus decoration).
	 */
	public static void paintParentBackground( Graphics g, JComponent c ) {
		Color background = getParentBackground( c );
		if( background != null ) {
			g.setColor( background );
			g.fillRect( 0, 0, c.getWidth(), c.getHeight() );
		}
	}

	/**
	 * Gets the background color of the first opaque parent.
	 */
	public static Color getParentBackground( JComponent c ) {
		Container parent = findOpaqueParent( c );
		// parent.getBackground() may return null
		// (e.g. for Swing delegate components used for AWT components on macOS)
		Color background = (parent != null) ? parent.getBackground() : null;
		if( background != null )
			return background;

		if( isAWTPeer( c ) ) {
			// AWT peers usually use component background, except for TextField and ScrollPane
			return c instanceof JTextField || c instanceof JScrollPane || c.getBackground() == null
				? SystemColor.window
				: c.getBackground();
		}

		return UIManager.getColor( "Panel.background" );
	}

	/**
	 * Find the first parent that is opaque.
	 */
	private static Container findOpaqueParent( Container c ) {
		while( (c = c.getParent()) != null ) {
			if( c.isOpaque() )
				return c;
		}
		return null;
	}

	/**
	 * Creates a not-filled rectangle shape with the given line width.
	 */
	public static Path2D createRectangle( float x, float y, float width, float height, float lineWidth ) {
		Path2D path = new Path2D.Float( Path2D.WIND_EVEN_ODD );
		path.append( new Rectangle2D.Float( x, y, width, height ), false );
		path.append( new Rectangle2D.Float( x + lineWidth, y + lineWidth,
			width - (lineWidth * 2), height - (lineWidth * 2) ), false );
		return path;
	}

	/**
	 * Creates a not-filled rounded rectangle shape and allows specifying the line width and the radius of each corner.
	 */
	public static Path2D createRoundRectangle( float x, float y, float width, float height,
		float lineWidth, float arcTopLeft, float arcTopRight, float arcBottomLeft, float arcBottomRight )
	{
		Path2D path = new Path2D.Float( Path2D.WIND_EVEN_ODD );
		path.append( createRoundRectanglePath( x, y, width, height, arcTopLeft, arcTopRight, arcBottomLeft, arcBottomRight ), false );
		path.append( createRoundRectanglePath( x + lineWidth, y + lineWidth, width - (lineWidth * 2), height - (lineWidth * 2),
			arcTopLeft - lineWidth, arcTopRight - lineWidth, arcBottomLeft - lineWidth, arcBottomRight - lineWidth ), false );
		return path;
	}

	/**
	 * Creates a filled rounded rectangle shape and allows specifying the radius of each corner.
	 */
	public static Shape createRoundRectanglePath( float x, float y, float width, float height,
		float arcTopLeft, float arcTopRight, float arcBottomLeft, float arcBottomRight )
	{
		if( arcTopLeft <= 0 && arcTopRight <= 0 && arcBottomLeft <= 0 && arcBottomRight <= 0 )
			return new Rectangle2D.Float( x, y, width, height );

		// limit arcs to min(width,height)
		float maxArc = Math.min( width, height ) / 2;
		arcTopLeft = (arcTopLeft > 0) ? Math.min( arcTopLeft, maxArc ) : 0;
		arcTopRight = (arcTopRight > 0) ? Math.min( arcTopRight, maxArc ) : 0;
		arcBottomLeft = (arcBottomLeft > 0) ? Math.min( arcBottomLeft, maxArc ) : 0;
		arcBottomRight = (arcBottomRight > 0) ? Math.min( arcBottomRight, maxArc ) : 0;

		float x2 = x + width;
		float y2 = y + height;

		// same constant as in java.awt.geom.EllipseIterator.CtrlVal used to paint circles
		double c = 0.5522847498307933;
		double ci = 1. - c;
		double ciTopLeft = arcTopLeft * ci;
		double ciTopRight = arcTopRight * ci;
		double ciBottomLeft = arcBottomLeft * ci;
		double ciBottomRight = arcBottomRight * ci;

		Path2D rect = new Path2D.Float( Path2D.WIND_NON_ZERO, 16 );
		rect.moveTo(  x2 - arcTopRight, y );
		rect.curveTo( x2 - ciTopRight, y,
					  x2, y + ciTopRight,
					  x2, y + arcTopRight );
		rect.lineTo(  x2, y2 - arcBottomRight );
		rect.curveTo( x2, y2 - ciBottomRight,
					  x2 - ciBottomRight, y2,
					  x2 - arcBottomRight, y2 );
		rect.lineTo(  x + arcBottomLeft, y2 );
		rect.curveTo( x + ciBottomLeft, y2,
					  x, y2 - ciBottomLeft,
					  x, y2 - arcBottomLeft );
		rect.lineTo(  x, y + arcTopLeft );
		rect.curveTo( x, y + ciTopLeft,
					  x + ciTopLeft, y,
					  x + arcTopLeft, y );
		rect.closePath();

		return rect;
	}

	/**
	 * Creates a rounded triangle shape for the given points and arc radius.
	 *
	 * @since 3
	 */
	public static Shape createRoundTrianglePath( float x1, float y1, float x2, float y2,
		float x3, float y3, float arc )
	{
		double averageSideLength = (distance( x1,y1, x2,y2 ) + distance( x2,y2, x3,y3 ) + distance( x3,y3, x1,y1 )) / 3;
		double t1 = (1 / averageSideLength) * arc;
		double t2 = 1 - t1;

		return createPath(
			lerp( x3, x1, t2 ), lerp( y3, y1, t2 ),
			QUAD_TO, x1, y1, lerp( x1, x2, t1 ), lerp( y1, y2, t1 ),
			lerp( x1, x2, t2 ), lerp( y1, y2, t2 ),
			QUAD_TO, x2, y2, lerp( x2, x3, t1 ), lerp( y2, y3, t1 ),
			lerp( x2, x3, t2 ), lerp( y2, y3, t2 ),
			QUAD_TO, x3, y3, lerp( x3, x1, t1 ), lerp( y3, y1, t1 ) );
	}

	/**
	 * Paints a chevron or triangle arrow in the center of the given rectangle.
	 *
	 * @param g the graphics context used for painting
	 * @param x the x coordinate of the rectangle
	 * @param y the y coordinate of the rectangle
	 * @param width the width of the rectangle
	 * @param height the height of the rectangle
	 * @param direction the arrow direction ({@link SwingConstants#NORTH}, {@link SwingConstants#SOUTH}
	 *        {@link SwingConstants#WEST} or {@link SwingConstants#EAST})
	 * @param chevron {@code true} for chevron arrow, {@code false} for triangle arrow
	 * @param arrowSize the width of the painted arrow (for vertical direction) (will be scaled)
	 * @param arrowThickness the thickness of the painted chevron arrow (will be scaled)
	 * @param xOffset an offset added to the x coordinate of the arrow to paint it out-of-center. Usually zero. (will be scaled)
	 * @param yOffset an offset added to the y coordinate of the arrow to paint it out-of-center. Usually zero. (will be scaled)
	 *
	 * @since 3
	 */
	public static void paintArrow( Graphics2D g, int x, int y, int width, int height,
		int direction, boolean chevron, int arrowSize, float arrowThickness,
		float xOffset, float yOffset )
	{
		// compute arrow width/height
		// - make chevron arrows one pixel smaller because coordinates are based on center of pixels (0.5/0.5)
		// - make triangle arrows one pixel taller (and round height up) to make them look stronger
		float aw = UIScale.scale( arrowSize + (chevron ? -1 : 0) );
		float ah = chevron ? (aw / 2) : UIScale.scale( (arrowSize / 2) + 1 );

		// rotate arrow width/height for horizontal directions
		boolean vert = (direction == SwingConstants.NORTH || direction == SwingConstants.SOUTH);
		if( !vert ) {
			float temp = aw;
			aw = ah;
			ah = temp;
		}

		// chevron lines end 1px outside of width/height
		// --> add 1px to arrow width/height for position calculation
		int extra = chevron ? 1 : 0;

		// compute arrow location
		float ox = ((width - (aw + extra)) / 2f) + UIScale.scale( xOffset );
		float oy = ((height - (ah + extra)) / 2f) + UIScale.scale( yOffset );
		float ax = x + ((direction == SwingConstants.WEST) ? -Math.round( -(ox + aw) ) - aw : Math.round( ox ));
		float ay = y + ((direction == SwingConstants.NORTH) ? -Math.round( -(oy + ah) ) - ah : Math.round( oy ));

		// paint arrow
		g.translate( ax, ay );
/*debug
		debugPaintArrow( g, Color.red, vert, Math.round( aw + extra ), Math.round( ah + extra ) );
debug*/
		Shape arrowShape = createArrowShape( direction, chevron, aw, ah );
		if( chevron ) {
			Stroke oldStroke = g.getStroke();
			g.setStroke( new BasicStroke( UIScale.scale( arrowThickness ) ) );
			drawShapePure( g, arrowShape );
			g.setStroke( oldStroke );
		} else {
			// triangle
			g.fill( arrowShape );
		}
		g.translate( -ax, -ay );
	}

	/**
	 * Creates a chevron or triangle arrow shape for the given direction and size.
	 * <p>
	 * The chevron shape is an open path that can be painted with {@link Graphics2D#draw(Shape)}.
	 * The triangle shape is a close path that can be painted with {@link Graphics2D#fill(Shape)}.
	 *
	 * @param direction the arrow direction ({@link SwingConstants#NORTH}, {@link SwingConstants#SOUTH}
	 *        {@link SwingConstants#WEST} or {@link SwingConstants#EAST})
	 * @param chevron {@code true} for chevron arrow, {@code false} for triangle arrow
	 * @param w the width of the returned shape
	 * @param h the height of the returned shape
	 *
	 * @since 1.1
	 */
	public static Shape createArrowShape( int direction, boolean chevron, float w, float h ) {
		switch( direction ) {
			case SwingConstants.NORTH:	return createPath( !chevron, 0,h, (w / 2f),0, w,h );
			case SwingConstants.SOUTH:	return createPath( !chevron, 0,0, (w / 2f),h, w,0 );
			case SwingConstants.WEST:	return createPath( !chevron, w,0, 0,(h / 2f), w,h );
			case SwingConstants.EAST:	return createPath( !chevron, 0,0, w,(h / 2f), 0,h );
			default:					return new Path2D.Float();
		}
	}

/*debug
	private static void debugPaintArrow( Graphics2D g, Color color, boolean vert, int w, int h ) {
		Color oldColor = g.getColor();
		g.setColor( color );
		g.fill( createRectangle( 0, 0, w, h, 1 ) );

		int xy1 = -2;
		int x2 = w + 1;
		int y2 = h + 1;
		for( int i = 0; i < 20; i++ ) {
			g.fillRect( 0, xy1, 1, 1 );
			g.fillRect( 0, y2, 1, 1 );
			g.fillRect( xy1, 0, 1, 1 );
			g.fillRect( x2, 0, 1, 1 );
			xy1 -= 2;
			x2 += 2;
			y2 += 2;
		}

		g.setColor( oldColor );
	}
debug*/

	/** @since 3 */ public static final double MOVE_TO    = -1_000_000_000_001.;
	/** @since 3 */ public static final double QUAD_TO    = -1_000_000_000_002.;
	/** @since 3 */ public static final double CURVE_TO   = -1_000_000_000_003.;
	/** @since 3 */ public static final double ROUNDED    = -1_000_000_000_004.;
	/** @since 3 */ public static final double CLOSE_PATH = -1_000_000_000_005.;

	/**
	 * Creates a closed path for the given points.
	 */
	public static Path2D createPath( double... points ) {
		return createPath( true, points );
	}

	/**
	 * Creates an open or closed path for the given points.
	 */
	public static Path2D createPath( boolean close, double... points ) {
		Path2D path = new Path2D.Float( Path2D.WIND_NON_ZERO, points.length / 2 + (close ? 1 : 0) );
		path.moveTo( points[0], points[1] );
		for( int i = 2; i < points.length; ) {
			double p = points[i];
			if( p == MOVE_TO ) {
				// move pointer to
				//    params: x, y
				path.moveTo( points[i + 1], points[i + 2] );
				i += 3;
			} else if( p == QUAD_TO ) {
				// add quadratic curve
				//    params: x1, y1, x2, y2
				path.quadTo( points[i + 1], points[i + 2], points[i + 3], points[i + 4] );
				i += 5;
			} else if( p == CURVE_TO ) {
				// add bezier curve
				//    params: x1, y1, x2, y2, x3, y3
				path.curveTo( points[i + 1], points[i + 2], points[i + 3], points[i + 4], points[i + 5], points[i + 6] );
				i += 7;
			} else if( p == ROUNDED ) {
				// add rounded corner
				//    params: x, y, arc
				double x = points[i + 1];
				double y = points[i + 2];
				double arc = points[i + 3];

				// index of next point
				int ip2 = i + 4;
				if( points[ip2] == QUAD_TO || points[ip2] == ROUNDED )
					ip2++;

				// previous and next points
				Point2D p1 = path.getCurrentPoint();
				double x1 = p1.getX();
				double y1 = p1.getY();
				double x2 = points[ip2];
				double y2 = points[ip2 + 1];

				double d1 = distance( x, y, x1, y1 );
				double d2 = distance( x, y, x2, y2 );
				double t1 = 1 - ((1 / d1) * arc);
				double t2 = (1 / d2) * arc;

				path.lineTo( lerp( x1, x, t1 ), lerp( y1, y, t1 ) );
				path.quadTo( x, y, lerp( x, x2, t2 ), lerp( y, y2, t2 ) );

				i += 4;
			} else if( p == CLOSE_PATH ) {
				// close path
				//    params: -
				path.closePath();
				i += 1;
			} else {
				// add line to
				//    params: x, y
				path.lineTo( p, points[i + 1] );
				i += 2;
			}
		}
		if( close )
			path.closePath();
		return path;
	}

	/**
	 * Calculates linear interpolation between two values.
	 *
	 * https://en.wikipedia.org/wiki/Linear_interpolation#Programming_language_support
	 */
	private static double lerp( double v1, double v2, double t ) {
		return (v1 * (1 - t)) + (v2 * t);
	}

	/**
	 * Calculates the distance between two points.
	 */
	private static double distance( double x1, double y1, double x2, double y2 ) {
		double dx = x2 - x1;
		double dy = y2 - y1;
		return Math.sqrt( (dx * dx) + (dy * dy) );
	}

	/**
	 * Draws the given shape with disabled stroke normalization.
	 * The x/y coordinates of the shape are translated by a half pixel.
	 *
	 * @since 2.1
	 */
	public static void drawShapePure( Graphics2D g, Shape shape ) {
		Object oldStrokeControl = g.getRenderingHint( RenderingHints.KEY_STROKE_CONTROL );
		g.setRenderingHint( RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE );

		g.translate( 0.5, 0.5 );
		g.draw( shape );
		g.translate( -0.5, -0.5 );

		g.setRenderingHint( RenderingHints.KEY_STROKE_CONTROL, oldStrokeControl );
	}

	/**
	 * Draws the given string at the specified location.
	 * The provided component is used to query text properties and anti-aliasing hints.
	 * <p>
	 * Use this method instead of {@link Graphics#drawString(String, int, int)} for correct anti-aliasing.
	 * <p>
	 * Replacement for {@code SwingUtilities2.drawString()}.
	 * Uses {@link HiDPIUtils#drawStringWithYCorrection(JComponent, Graphics2D, String, int, int)}.
	 */
	public static void drawString( JComponent c, Graphics g, String text, int x, int y ) {
		HiDPIUtils.drawStringWithYCorrection( c, (Graphics2D) g, text, x, y );
	}

	/**
	 * Draws the given string at the specified location underlining the specified character.
	 * The provided component is used to query text properties and anti-aliasing hints.
	 * <p>
	 * Replacement for {@code SwingUtilities2.drawStringUnderlineCharAt()}.
	 * Uses {@link HiDPIUtils#drawStringUnderlineCharAtWithYCorrection(JComponent, Graphics2D, String, int, int, int)}.
	 */
	public static void drawStringUnderlineCharAt( JComponent c, Graphics g,
		String text, int underlinedIndex, int x, int y )
	{
		// scale underline height if necessary
		if( underlinedIndex >= 0 && UIScale.getUserScaleFactor() > 1 ) {
			g = new Graphics2DProxy( (Graphics2D) g ) {
				@Override
				public void fillRect( int x, int y, int width, int height ) {
					if( height == 1 ) {
						// scale height and correct y position
						// (using 0.9f so that underline height is 1 at scale factor 1.5x)
						height = Math.round( UIScale.scale( 0.9f ) );
						y += height - 1;
					}

					super.fillRect( x, y, width, height );
				}
			};
		}

		HiDPIUtils.drawStringUnderlineCharAtWithYCorrection( c, (Graphics2D) g, text, underlinedIndex, x, y );
	}

	public static boolean hasOpaqueBeenExplicitlySet( JComponent c ) {
		boolean oldOpaque = c.isOpaque();
		LookAndFeel.installProperty( c, "opaque", !oldOpaque );
		boolean explicitlySet = c.isOpaque() == oldOpaque;
		LookAndFeel.installProperty( c, "opaque", oldOpaque );
		return explicitlySet;
	}

	/**
	 * Returns whether shared UI delegates are used.
	 *
	 * @since 1.6
	 */
	public static boolean isUseSharedUIs() {
		return useSharedUIs;
	}

	/**
	 * Specifies whether shared UI delegates are used.
	 * This does not change already existing UI delegates.
	 *
	 * @since 1.6
	 */
	public static boolean setUseSharedUIs( boolean useSharedUIs ) {
		boolean old = FlatUIUtils.useSharedUIs;
		FlatUIUtils.useSharedUIs = useSharedUIs;
		return old;
	}

	/**
	 * Creates a shared component UI for the given key and the current Laf.
	 * Each Laf instance has its own shared component UI instance.
	 * <p>
	 * This is for GUI builders that support Laf switching and
	 * may use multiple Laf instances at the same time.
	 */
	public static ComponentUI createSharedUI( Object key, Supplier<ComponentUI> newInstanceSupplier ) {
		if( !useSharedUIs )
			return newInstanceSupplier.get();

		return sharedUIinstances
			.computeIfAbsent( UIManager.getLookAndFeel(), k -> new IdentityHashMap<>() )
			.computeIfAbsent( key, k -> newInstanceSupplier.get() );
	}

	/**
	 * Returns whether the component UI for the given component can be shared
	 * with other components. This is only possible if it does not have styles.
	 */
	public static boolean canUseSharedUI( JComponent c ) {
		return !FlatStylingSupport.hasStyleProperty( c );
	}

	//---- class RepaintFocusListener -----------------------------------------

	public static class RepaintFocusListener
		implements FocusListener
	{
		private final Component repaintComponent;
		private final Predicate<Component> repaintCondition;

		public RepaintFocusListener( Component repaintComponent, Predicate<Component> repaintCondition ) {
			this.repaintComponent = repaintComponent;
			this.repaintCondition = repaintCondition;
		}

		@Override
		public void focusGained( FocusEvent e ) {
			if( repaintCondition == null || repaintCondition.test( repaintComponent ) )
				HiDPIUtils.repaint( repaintComponent );
		}

		@Override
		public void focusLost( FocusEvent e ) {
			if( repaintCondition == null || repaintCondition.test( repaintComponent ) )
				HiDPIUtils.repaint( repaintComponent );
		}
	}

	//---- class NonUIResourceBorder ------------------------------------------

	private static class NonUIResourceBorder
		implements Border
	{
		private final Border delegate;

		NonUIResourceBorder( Border delegate ) {
			this.delegate = delegate;
		}

		@Override
		public void paintBorder( Component c, Graphics g, int x, int y, int width, int height ) {
			delegate.paintBorder( c, g, x, y, width, height );
		}

		@Override
		public Insets getBorderInsets( Component c ) {
			return delegate.getBorderInsets( c );
		}

		@Override
		public boolean isBorderOpaque() {
			return delegate.isBorderOpaque();
		}
	}
}
